Useful tricks

In this section, we gather useful tips and tricks related to both data recovery in general and some specific situations you may face recovering data on the day-by-day basis.

No special arranging by importance or complexity is provided in this section, you may start with any lesson. Additionally, lessons in this section are accompanied by neither practical tasks nor tests, only video lessons and summaries are available.

Also, you may find helpful to have at hand a textbook Logical Data Recovery, which formed the basis of this course.

Lesson 1 - Units of measurement

From this lesson, you learn about units of measurement important in data recovery, namely bits, bytes, and sectors. Also, we provide information about the difference between physical and "standard" sectors.

Lesson 2 - NAS and iSCSI

From this lesson, you learn about the difficulties you may encounter when recovering a NAS, which was used as an iSCSI target. We discuss how to recognize that iSCSI is involved and what approach should be used to successfully recover NAS data.

Lesson 3 - Xen recovery

From this lesson, you learn where you can meet Xen Server, how data storage is organized in such a device, and what approaches should be used to successfully recover data from Xen servers.

Lesson 4 - Metadata in CoW filesystems

From the lesson, you learn the specifics of storing metadata both in modern filesystems using the copy-on-write (CoW) feature and in old non-CoW filesystems. Additionally, the possibility of correct timestamps recovery on BTRFS filesystem is discussed in detail.

Lesson 5 - By popular demand

Questions repeatedly arise in our technical support form the topics discussed in this lesson, such as whether it is possible to troubleshoot a hardware problem with software alone, the chance to recover part of the data when too many disks failed in a RAID, and so on.

Lesson 6 - Limits of logical data recovery

This lesson covers limits of logical data recovery both for automatic and manual modes. The chart depicting how the number of parameters describing a storage system depends on the volume size is provided for various storage systems.

Lesson 7 - Durability of data in modern storage systems

This lesson covers various background processes, which destroy data in modern storage systems from Drobo BeyondRAID and Storage Spaces to regular hard drives.

Lesson 8 - How to create an image file of damaged drive

In this lesson we will show how to set the correct settings when creating an image of a physically damaged disk.

Case Study 1 – Why it is important to verify MD metadata

We consider the case where md metadata looks good but filesystem recovery failed to bring healthy files. Quick and simple tests helping to verify the consistency of md RAID metadata are discussed.

Case Study 2 – Addonics HPM-XU Recovery

We consider the case associated with recovering data from a RAID5 configured by Addonics HPM-XU RAID controller. All the RAID recovery procedures were used in full and as a result an unusual block size was detected.

Case Study 3 – Data recovery from a NetGear NAS used as ESX datastore

We discuss the specific of recovering data from a NetGear ReadyNAS which is used as datastore for ESX VMware.

Case Study 4 - Data recovery from RAID1E

In this Case Study we discuss a case involving data recovery from a RAID1E array created by the LSI SAS3041e controller.

Case Study 5 - HP Smart Array controllers and delay parity

We discuss the specifics of recovering RAID configuration used in HP Smart Array controllers.